Add protected interaction evidence and measured debugging phases

docs/interaction-evidence.md

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+# Protected interaction evidence
+
+Administrators separately enable `evidence.enabled`, `captureDownloads` and
+`captureInteractions` through reviewed signed policy. All are off by default.
+Interaction capture currently covers confirmed guarded copy/cut/paste and
+completed agent clicks. It is not a recording of every physical user click.
+
+Ordinary clipboard audit distinguishes authorization before the effect from
+completion after the effect. Protected completion metadata contains website
+origin, opaque session ID, action, structural target tag/role, bounded viewport
+coordinates and optional byte count. Paths, queries, fragments, field values,
+document text, selectors, labels and content hashes are excluded. Sensitive
+fields do not produce this capture.
+
+Agent completion capture is a separate audit phase from RPC completion; two
+events do not mean two clicks. The native fixture verifies one click effect.
+The server binds evidence to the accepted device event, action, source, session
+and completed outcome. New writes reject raw interaction content. Existing
+encrypted legacy evidence remains readable through restricted audited access.
+
+The source event and typed protected payload are persisted in one DPAPI-protected
+local queue record. Delivery acknowledges the ordinary event first and uses the
+protected post-quantum management evidence channel. Policy and enrollment are
+rechecked throughout delivery. Disabling interaction capture aborts matching
+in-flight delivery and removes pending interaction evidence while preserving
+ordinary audit and separately allowed download evidence. Existing retained
+records still follow retention, legal-hold and purpose-bound analyst access.
+
+Debug traces measure capture, challenge, encryption, send and acknowledgement,
+with correlated server decrypt/store phases. These timing spans carry no raw
+interaction contents. Evidence retention is independent of diagnostics.
+
+Remaining coverage includes general physical interaction observation, controlled
+content capture, all browser convenience clipboard paths and a proven scoped
+credential-submission exception. Do not assume this feature is full page replay
+or blanket password-field authorization.